Polycrystalline Pb(Zr,Ti)O3 (PZT) films 70–80 nm thick on (111)Ir/TiO2/SiO2/Si substrates were prepared at 415 °C by metalorganic chemical vapor deposition (MOCVD). At 3 V, the remanent polarization (Pr) of the as-deposited films was approximately 22 μC/cm2. Inserting PbTiO3 seeds between the PZT films and Ir bottom electrodes improved the crystallinity of the films markedly but improved their ferroelectric properties only slightly. Low-temperature postannealing, on the other hand, even at 400 °C (i.e., below the deposition temperature), improved Pr values and hysteresis loop shapes without obviously improving the crystallinity of the films. The electrical properties were improved even more when the films were annealed at 500 °C. These results suggest that the low-temperature processing and sub-100-nm film thickness needed for making three-dimensionally structured ferroelectric capacitors can be obtained by using low-temperature MOCVD to deposit PZT films, and then annealing those films at a temperature no greater than 500 °C.